New ETA shows 90kt LLJ across Midsouth 12z Thursday!

[ALhurricane]

Now here is something you don't see everyday..

http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_084l.gif

A 70-90kt 850 jet?! Holy cow!

Combine this with 500-1000 j/kg of CAPE and we've got a potential severe weather outbreak.

[jkt21787]

That is quite concerning AL, if we get any sunshine Wednesday we better watch out here. Haven't had a real good dose of severe weather since those tornadoes in late October.

Still looks like a squall line event more than likely, although I havent looked at the new ETA. What are your thoughts?

[ALhurricane]

A squall line is a good bet. I am also concerned about discrete supercells ahead of the line...especially if we get a lot of sun during the day on Wednesday. I am concerned about torandoes due to possible low LCL levels and very strong low level shear.

[jkt21787]

Thanks for the quick reply. I did see the rather low LCL on a forecast sounding and was a little concerned. Well, the jet dynamics and wind shear will definitely be there, so a little instability is all that is needed. Certainly the squall line could be quite intense with a jet that strong. Will see what the SPC says on the upcoming day 3 outlook.

[ALhurricane]

I would be VERY surprised if a slight risk was not put out for Day 3.

BTW...00z GFS has a 60-80kt jet.

Regarding instability. With the shortwave looking to pass across the midsouth, this will help to steepen lapse rates. Model guidance has been increasing instability parameters each run. It's still a few days out, but things are looking more ominous with time.

[jkt21787]

Well, certainly each model run has been more ominous, so the next few days are going to be quite intresting.

Are you on duty this week? Looks to be a fun one

[ALhurricane]

Yeah... I am on the public forecast desk Tuesday and Wednesday. Talk about luck of the draw.

[Stormsfury]

Even w/out those kinds of LLJ's, the contrast in airmass alone would throw off a red-flag (no surprise to me that such contrasts and also w/prolonged warmth and beautiful usually ends w/a bang, and sometimes w/damaging consequences) ... combine this with strong WAA out ahead of the front, along w/good moisture and of course, let's prog a 70 kt 850mb jet, and a general veering of winds w/height, and the ingredients are increasingly coming together for a significant SVR WX outbreak ...

70 kt 850mb jet w/a squall line would be capable of producing 60 kt winds at the SFC, especially w/strong convection, and the ingredients are there for possible tornadoes, some of those being strong (F2-F3) ...

[jkt21787]

Definitely good timing there. Good luck to you, I know you folks down there will be closely watching it and issue whatever needs to be issued.

[jkt21787]

Even w/out those kinds of LLJ's, the contrast in airmass alone would throw off a red-flag (no surprise to me that such contrasts and also w/prolonged warmth and beautiful usually ends w/a bang, and sometimes w/damaging consequences) ... combine this with strong WAA out ahead of the front, along w/good moisture and of course, let's prog a 70 kt 850mb jet, and a general veering of winds w/height, and the ingredients are increasingly coming together for a significant SVR WX outbreak ...

70 kt 850mb jet w/a squall line would be capable of producing 60 kt winds at the SFC, especially w/strong convection, and the ingredients are there for possible tornadoes, some of those being strong (F2-F3) ...

Yep, more and more of the needed ingredients are coming together for this to be a good wintertime outbreak. Let's hope this doesn't have shades of January 1999. Not sure if anyone remembers that one, but there were two outbreaks within a few days of each other. One on the 17th which had a F-4 in Jackson, TN then the big one on the 21-22, I think there were well over 40 tornadoes just in my area alone, one of the worst on record.

[ALhurricane]

Agreed Stormsfury. I would be concerned if we just had a 40-50kt jet, but with 70kt or so possible, it has the capability of a making a dangerous situation more dangerous. It looks like all modes of severe weather will occur with this event.

jkt.. rest assured we always strive to do our best

[jkt21787]

jkt.. rest assured we always strive to do our best

I know you always do your best, I am glad to be served by your office. You have one of the better warning programs I have seen. I remember some of the warnings issued back in October, knowing how serious they sounded, and that helps the public and media out with getting the needed info. Plus, I have read where you have an IM service with the TV stations here, thats what I call cooperation.

You should all be commended for your great job.

[ALhurricane]

Thanks for your kind words. October 18th was a night I won't soon forget. I think the city of Dyersburg should feel very fortunate that tornado was not as strong as it could have been. Absolutely one of the best looking supercells we have seen in this area.

Our IM service allows a quick link between us and the tv media and emergency managers. It has been a very valuable asset to the office and has helped us to get out storm reports much faster.

[Stormsfury]

Yep, more and more of the needed ingredients are coming together for this to be a good wintertime outbreak. Let's hope this doesn't have shades of January 1999. Not sure if anyone remembers that one, but there were two outbreaks within a few days of each other. One on the 17th which had a F-4 in Jackson, TN then the big one on the 21-22, I think there were well over 40 tornadoes just in my area alone, one of the worst on record.

January 1999 stands out w/the record for most tornadoes in that month ... an astounding 212 in the US. (18 fatalities) ... (source. SPC)

Agreed Stormsfury. I would be concerned if we just had a 40-50kt jet, but with 70kt or so possible, it has the capability of a making a dangerous situation more dangerous. It looks like all modes of severe weather will occur with this event.

jkt.. rest assured we always strive to do our best

most definitely, Jason. a strong squall line w/that kind of LLJ produces a widespread wind damage event alone. Those progs by the ETA/GFS come to fruitation, we maybe easily dealing with a derecho.

SF

[wxguy25]

Furthermore, any instability would just act to exacerbate the situation. There should be sufficient CVA ahead of the s/w to develop strong/severe convection by its self.

[jkt21787]

Those supercells in the Dyersburg area were quite amazing. I have saved Level II and III images from that night in the radar program I use here at home.

Need to definitely keeep an eye out on this one.

[PurdueWx80]

I think there may be a bit too much shear for there to be a widespread outbreak, especially if we're talking about tornadic activity. If this were March or April I think it would be a different story (given warmer low-level temps and higher low-level moisture). I do agree that a squall line will be more likely, but storm motions will be between N and NE (most likely NNE) so that will limit the amount of near-surface storm relative helicity even though there is decent directional shear above the surface. This is the type of scenario where I see a VERY narrow line of convection right along the convergence associated w/ the front...with widespread showers and storms ahead of it. I would imagine that, given a 60-90 kt jet in the TN and OH Valleys, damaging winds would be likely right along the front/squall line.